• Volume 14, Issue 6

      June 1980,   pages  425-521

    • Electromagnetic form factors of3He and3H

      S S Mehdi V K Gupta

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      The electric and magnetic form factors of3He and3H are calculated with 3-nucleon wave functions obtained from the solution of Schrödinger equation with separable potentials of two different shapes which have already been employed in the coulomb energy calculation. The effect of important meson exchange corrections is evaluated and their dependence on the wave function studied. The form factors can depend rather sensitively on the nucleon form factors as well, and this dependence is studied by using two different parametrisations for the latter.

    • Quark model predictions on the masses of heavier vector mesons

      C P Singh Satish Kanwar M P Khanna

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      We use the quark model considerations of Federman, Rubinstein and Talmi and the relation (mψ/mϕ)≃(mϒ/mψ)≃(mϒ/mϒ) to compute the masses of beautiful and tasty vector mesons.

    • Magnetic moments ofb-quark baryons in broken SU(5) symmetry

      Mubarak Ahmad Abdul Samad G Q Sofi

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      The magnetic moments ofb-quark baryons within the framework of five quark models are derived. Also the transition magnetic moments of variousb-quark baryons are calculated.

    • ESR studies of Cu2+ doped in triglycine calcium bromide single crystals

      V Chandra Mouli G Sivarama Sastry

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      Electron spin resonance studies were carried out on Cu2+ doped triglycine calcium bromide. The spectra recorded at room temperature revealed well-resolved hyperfine spectra of63Cu superposed with super-hyperfine lines due to14N nuclei. The spin Hamiltonian parameters are evaluated. It was concluded that the Cu2+ enters the lattice interstitially.

    • Electrical transport properties of CuWO4

      R Bharati R Shanker R A Singh

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      The temperature dependence of the electrical conductivity, thermoelectric power and dielectric constant of the antiferromagnetic CuWO4 have been studied in the temperature range 300–1000 K. The conductivity results can be summarised by the equations σI=6.31 × 10−3 exp (−0.29 eV/kT) ohm−1 cm−1 in the temperature range 300–600 K and σII=3.16 × 105 exp (−1.48 eV/kT) ohm−1 cm−1 between 600 K and 1000 K. The thermoelectric power can be expressed byθ=[− 1.25 (103/T) + 3.9] mV/K. Initially dielectric constant increases slowly but for high temperatures its increase is fast.

    • L-shell internal excitation accompanyingL-capture

      R G Kulkarni

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      TheL-shell internal excitation accompanyingL-capture has been treated relativistically by the use of hydrogenic wave functions. Numerical calculations for the nuclides37Ar,55Fe,77Ge,131Cs,157Tb,165Er,179Ta and193Pt have been performed for the first-time. The present calculations show that doubleLi-hole production probability decreases with increasing atomic number and it is almost independent of transition energy for a particular shell. Possible experiments to detect this phenomenon in atoms for whichK-K processes are energetically forbidden are discussed briefly.

    • Steady low shear rate cholesteric flow normal to the helical axis

      U D Kini

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      Steady cholesteric flow at low shear rate normal to the helical axis is studied analytically for shear flow and plane Poiseuille flow on the basis of Leslie’s continuum theory. For general asymmetric solutions the angle made by the director at the sample centre with the primary flow is found to profoundly affect the oscillations of the apparent viscosity with pitch for pitches of the order of the sample thickness. The velocity and orientation profiles are also found to change drastically. These considerations may be important in flow experiments on long pitch cholesterics.

    • Liquid fluorine properties by the hardsphere model with attractive interactions

      B K Sharma

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      We test the validity of an approximate equation of state of real fluids and the expression for surface tension of hardsphere liquids with attractive interactions derived by Sharma and others by obtaining expressions for isothermal compressibility,C1-parameter and acoustical parameter and relate them to microscopic Grüneisen parameter. The calculated values for liquid fluorine show fair agreement with experimental values.

    • Determination of the optical constants of selenium films

      S Mokhtar W Osman

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      The optical constants of evaporated Se films are calculated following Valeev’s method and applied to Se in the visible region. The calculated values are in good agreement with published data.

    • Coherent information processing by a pair of lenses in spherical wave illumination

      R S Kasana T C Gupta

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      A coherent optical information system has been analysed using the Fresnel diffraction theory. Considering the spherical wave illumination, the same system is used for spatial filtering and subsequent reimaging. The conditions for locating the spatial frequency plane and the image plane have been pointed out. The scale of the Fourier transform can be controlled by three degrees of freedom. The final image formed is inverted and magnified with respect to the input signal. The present analysis has been compared with those of Pernick and Moharir. Aberrations involved have also been discussed.

    • Diffusion of Ag through Se and its effect on interferometric thickness measurement

      S Mokhtar S Abdel-Aziz

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      The effect of diffusion of silver through Se thin films, on the visibility of two and multiple beam interference fringes has been studied. For thickness measurements, Al has been found to be a suitable overcoating metallic layer as it does not diffuse through Se. The thickness was measured by multiple beam fringes at reflection.

    • The infrared spectra of tutton salts 1. A comparative study of (NH4)2 M″(SO4)2·6H2O (M″=Ni, Co or Mg)

      B Singh Shashi P Gupta B N Khanna

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      The infrared spectra of (NH4)2M″(SO4)2.6H2O has been analysed in the region 4000–250 cm−1. The dynamics of each crystal has been discussed in terms of 234 phonon modes, including 3 acoustical ones, using the unit cell approximation. The ambiguity in the assignments of the bands in the region 900–500 cm−1 has been removed by assigning the bands in this region to the libratory modes of H2O molecules. It has been concluded that the NH4+ and SO42− ions have a symmetry lower thanTdand also the complex [M″(H2O)6]2+ has a symmetry lower than Oh. The hydrogen bonding is the strongest in the Ni-salt and the weakest in the Mg-salt.

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